634 Haddon and Shackleton — A Revision of the British Actiiiice. 



SYSTEMATIC ACCOUNT OF THE BRITISH ZOANTHE^E. 



ZOANTHID^. 



I. Bkachycnemin^. (None British.) 

 II. Macrocnemin^. 



EPIZOANTHUS, Gray, 1867. 



Spongia (pars), Johnston, 18ci4. Sidisia, Gray, 1858. 



Dysidea ? (pars), Johnston, 1842. Carolia, Gray, 1867. 



Mammillifera (pars), Auct. Polythoa (pars), Andres, 1884. 



ZoANTHUS (pars), Auct. Palythoa (pars), Carus, 1884. 



Macrocnemic Zoanthese, with a single mesogloeal sphincter muscle. The body- 

 wall is incrusted ; the ectoderm is usually continuous, but may be discontinuous ; 

 cell-islets in the mesogloea. Dioecious. Polyps connected by coenenchyme, which 

 may be band-like, incrusting, or greatly reduced as in the free forms. 



The genus Epizoanthus was established by Gray in 1867 for incrusted Zoanthese : 

 " II. coral attached ; cells arising from a foliaceous expanded base. . . . The base 

 expanded foliaceous (parasitic on shells) ; the cells cylindrical, simple, separate 

 from each other from the base ; tentacles numerous " (p. 237). -E. papillosus, Johnst., 

 is his type. Verrill adopted Gray's genus. At first Hertwig (1882) agreed with 

 Verrill in using this term to denote incrusted forms which rose above their 

 coenenchyme. After Erdmann's investigations, he (1888) restricted the genus to 

 macrocnemic Zoanthese, with "Integument incrusted, coenenchyme (mostly?) 

 lamellar ; sphincter simple, mesogloeal ; mesenteries arranged on the macrotype ; 

 colonies (mainly ?) parasitic " (p. 37). We have studied the type species of this 

 genus, and find that it does conform to Erdmann's and Hertwig's definition of the 

 genus. We may add that all observers have agreed in relegating to this genus all 

 those incrusted Zoanthese which form carcinsecia. 



In 1858 Gray erected the genus Sidisia for free Zoanthese, " which may be 

 characterized by the emission of buds on the surface of the cylindrical body " 

 (p. 532), 8. barleei being the sole species. He considered that this species 

 "evidently belongs to quite a different grouj)" from Dysidea jjapillosa, Johnst., 

 which Mr. Barlee (m litt.) informed Gray " was a Zoanthus, allied to the genus 

 Mammillifera of Lesueur," an opinion which Gray adopted. 



Our investigations prove that S. barleei is only a variety of E. incrustatus {— K 

 papillosus). We do not propose to keep the name Sidisia for the genus, although it 

 has priority, and for this reason : it was solely erected for a species which is only 



